Messages in this thread | | | Date | Tue, 13 Jan 2009 02:47:23 +0100 | From | Ingo Molnar <> | Subject | Re: PCI, ACPI, IRQ, IOAPIC: reroute PCI interrupt to legacy boot interrupt equivalent |
| |
* Jon Masters <jcm@redhat.com> wrote:
> On Mon, 2009-01-12 at 15:36 -0800, Eric W. Biederman wrote: > > > This hardware behavior is not specific to boot interrupts or Intel. > > It's not specific to Intel, but it is a specific compatibility behavior. > > > Is this case really so interesting and compelling that we want to > > fight through and figure what we need to do to make this work reliably > > on every x86 chipset? > > How else do you propose implementing IRQ handling in e.g. the RT kernel? > We get a hardware interrupt, we can't FastEOI, we can't process > synchronously, we can't do all of those things you might expect. > Implementing RT requires that we delay handling of the IRQ until > arbitrarily later in the future when we get around to it.
a number of mainline drivers also mask/unmask irqs from within the IRQ handler. It's not particularly smart in a native driver, but can happen - and if we get an active line after that point (and this can happen because the driver is active), we are in trouble.
Ingo
| |